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Medical Dosimetry 37 (2012) 233-239

Medical Dosimetry

journal homepage: www.meddos.org

Postmastectomy radiotherapy with integrated scar boost using helicaltomotherapy

Yi Rong, Ph.D.,�,† Poonam Yadav, M.Sc.,�,‡,§ James S. Welsh, M.S., M.D.,�,†,‡ Tasha Fahner, C.M.D.,† andBhudatt Paliwal, Ph.D.�,‡

*Department of Human Oncology and ‡Department of Medical Physics, University of Wisconsin, Madison, Madison, WI; †University of Wisconsin, Riverview Cancer Center, WisconsinRapids, WI; and §Vellore Institute of Technology University, Vellore, Tamil Nadu, India

A R T I C L E I N F O

Article history:

A B S T R A C T

The purpose of this study was to evaluate helical tomotherapy dosimetry in postmastectomy patients

Received 17 January 2011Accepted 06 September 2011

undergoing treatment for chest wall and positive nodal regions with simultaneous integrated boost (SIB) inthe scar region using strip bolus. Six postmastectomy patients were scanned with a 5-mm-thick strip boluscovering the scar planning target volume (PTV) plus 2-cm margin. For all 6 cases, the chest wall received a

total cumulative dose of 49.3–50.4 Gy with daily fraction size of 1.7–2.0 Gy. Total dose to the scar PTV wasprescribed to 58.0–60.2 Gy at 2.0–2.5 Gy per fraction. The supraclavicular PTV and mammary nodal PTVreceived 1.7–1.9 dose per fraction. Two plans (with and without bolus) were generated for all 6 cases. Togenerate no-bolus plans, strip bolus was contoured and overrode to air density before planning. The setupreproducibility and delivered dose accuracy were evaluated for all 6 cases. Dose-volume histograms wereused to evaluate dose-volume coverage of targets and critical structures. We observed reduced aircavities with the strip bolus setup compared with what we normally see with the full bolus. Thethermoluminescence dosimeters (TLD) in vivo dosimetry confirmed accurate dose delivery beneath thebolus. The verification plans performed on the first day megavoltage computed tomography (MVCT)image verified that the daily setup and overall dose delivery was within 2% accuracy compared withthe planned dose. The hotspot of the scar PTV in no-bolus plans was 111.4% of the prescribed doseaveraged over 6 cases compared with 106.6% with strip bolus. With a strip bolus only covering thepostmastectomy scar region, we observed increased dose uniformity to the scar PTV, higher setupreproducibility, and accurate dose delivered beneath the bolus. This study demonstrates the feasibility of usinga strip bolus over the scar using tomotherapy for SIB dosimetry in postmastectomy treatments.

Published by Elsevier Inc. on behalf of American Association of Medical Dosimetrists.

Keywords:Helical tomotherapyStrip bolusPostmastectomy radiotherapyIn vivo dosimetrySimultaneous integrated boost

Ts(

Introduction

Recent randomized trials reveal that after mastectomy, postopera-tive locoregional radiation therapy improves survival in women withnode-positive breast cancer receiving adjuvant systemic therapy.1-3

Improving overall survival and preventing cancer recurrence inthe chest wall, mastectomy scar, and the regional nodes, such asthe axillary, supraclavicular, and internal mammary nodes, are themain rationale for postmastectomy radiation therapy.4,5 Tangen-tial delivery of radiation to the chest wall to minimize the amountof lung and heart tissue exposure has gained impetus in recent

Yi Rong has received travel sponsorship from TomoTherapy, Inc. James S. Welshas received honoraria for speaking for TomoTherapy, Inc.

Reprint requests to: Yi Rong, Ph.D., 300 W 10th Avenue, Columbus, Ohio

3211.

E-mail: rong@humonc.wisc.edu; yi.rong@osumc.edu

0958-3947/$ – see front matter Published by Elsevier Inc. on behalf of American Associationdoi:10.1016/j.meddos.2011.09.001

years.6 However, it is challenging to obtain uniform dose distribu-tion with tangential beams because of the patient’s anatomy andvariable depths of planning target volume (PTV) beneath the skin.In such cases, bolus can be used for increasing dose uniformity tothe mastectomy scar and subcutaneous tissues. The use of bolus,particularly over gross tumor nodules and incision scar area, isadvisable.7 Per the American Association of Physicists in Medicineask Group 25, the parameters such as energy, field size, and bolushould be selected so the target volume is encompassed within 90%or any other appropriate minimum dose) of the prescribed dose.8

Bolus usage helps in depositing the maximum dose on the skinsurface rather than at a certain depth,9-12 although no agreementhas been achieved in the clinical survey of optimal application ofbolus thickness and frequency.13 The difficulties with bolus are theaccuracy and reproducibility of positioning the bolus without any

air gaps between the skin and bolus. The surface dose can vary from

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Y. Rong et al. / Medical Dosimetry 37 (2012) 233-239234

0�10% depending on the amount of air gap between the bolus andskin surface.14-16

The common dose regimen for breast treatment is 50 Gy within5 weeks at 2 Gy/fraction given 5 days/week. An additional boost of10–16 Gy in 5 fractions with electrons, given to the mastectomyincision, has shown significantly lower local recurrence rate, espe-cially for patients with close or positive mastectomy margins.5 Theelical tomotherapy Hi-ART II machine (TomoTherapy, Inc, Madi-on, WI) uses rotational intensity-modulated beams to deliver op-imized dose distributions and has been widely used for many can-er sites.17-24 Recent studies have shown that tomotherapy mayserve as a feasible alternative to treat postlumpectomy or postmas-tectomy patients who have been treated conventionally with elec-trons, static photon beams, or a combination of the two.18,25-32 Theumor control probability and the normal tissue complicationrobability with tomotherapy are comparable with mixed-beamlanswith greater dose homogeneity (p � 0.001), whichmay trans-ate into improved cosmetic outcomes.27 Moreover, tomotherapyis proved to be feasible for treating simultaneous integrated boost(SIB) for breast-conserving treatment with adequate tumor cover-age and significant normal tissue sparing.18,32 It is reported thatbecause of the characteristics of the tomotherapy beam and deliv-ery technique, chest wall tomotherapy treatment plans showedadequate skin dose, more than 75% of the prescribed PTV dose, evenwithout the bolus.33 For postmastectomy patients, there is a sub-stantial risk for recurrence at the chest wall, with most recurrencesoccurring in the skin.34 The main concern from a dosimetric per-spective is the 3�13% overestimation in the calculated dose fromtomotherapy planning system for the superficial regions.35,36

Whether the bolus material would alleviate the underdosing issueis still an unresolved question to many radiation oncologists. Ini-

Fig. 1. A 5-mm strip bolus covering the scar PTV area plus 2-cm margin.

able 1atient selection data and prescription to chest wall, scar PTV, mammary nodes and ax

Pt. #TumorLocation Age (y) Chemotherapy

Total txFractions

Ch

V

1 Left breast 47 Yes 28 362 Left breast 60 Yes 28 403 Right breast 75 Yes 28 384 Right breast 79 Yes 28 305 Right breast 55 Yes 25 406 Right breast 42 Yes 28 38

Average 60 — — 374.2

tially in our institution, we experienced that using a large sheet ofbolus introduced large air cavities and they are not reproduciblethroughout the treatment. To achieve sufficient dose to the post-mastectomy scar region as well as setup reproducibility, we testedthe use of strip bolus in 6 patients who underwent postmastectomyradiotherapy (PMRT) with SIB and compared the dose distributionson plans with and without the strip bolus.

Methods and materials

Patient selection and prescription

Six patients with locally advanced breast cancer treated with postmastectomychestwall and regional nodal irradiationwere retrospectively reviewed and studied. Allpatients, with an average age of 60 years [42, 79] at the time of treatment, weresimulated on a kilo-voltage computed tomography (kVCT) scanner while lying insupine position with both arms overhead. As shown in Fig. 1 5-mm-thick strip bolusSuperflab, density 1.02 g/cm3) covering the scar PTV plus 2-cm margin was used athe time of CT simulation, as well as treatment. This bolus material, relatively freerom inelastic strain for normal stresses and tissue equivalent, is comfortable toatients and flexible without drying out. A Vac-Loc (Civco Medical Solutions, Ka-ona, IA) immobilization cushion was used for reproducibility of the patient setupuring treatment.

Patients were treated with 28 fractions of image-guided intensity-modulated ra-iotherapy (IMRT) plans with strip bolus using the helical tomotherapy unit, withdjuvant chemotherapy. For all 6 cases, the chest wall received a total cumulative dosef 49.3–50.4 Gy with daily fraction size of 1.7–2.0 Gy. Total dose to the scar PTV wasrescribed to 58.0–60.2 Gy at 2.0–2.5 Gy per fraction. The supraclavicular PTV andammary nodal PTV received 1.7–1.9 dose per fraction. Chest wall target size varied

rom 303.9�404.3 cm3, with a mean of 374.2 cm3. Similarly, the scar PTV varies from27.6�51.5 cm3, with amean of 41.9 cm3. Themammary nodes and axilla-supraclavicalnodes had an average size of 24.8 (range 11.5–35.5) cm3 and 180.2 (range 88.2–239.2)m3, respectively. The site of treatment, age, number of fractions, volume (V), andprescription (P) are briefly tabulated in Table 1.

Treatment planning

CT images were exported to the ADAC Pinnacle3 planning station (version 8.0 m,Philips Radiation Oncology Systems, Madison, WI) for contouring. The PTVs includethe postmastectomy scar with a 3�5-mm margin (not extending out of patient’sskin), chest wall, and supraclavicular/mammary nodes with a 4�8-mm margin.Organs at risk (OARs) include spinal cord, heart, lungs, and contralateral breast (Fig.2). The kVCT image and contours were exported to tomotherapy for planning (Hi-ART TomoTherapy, version 3.5.3). All plans used 2.5-cm field width, 0.287 pitch, andmodulation factor of 1.7�2.0. The parameters used for planning are based on ourexperience and recommendations from the literature.17-19,21,27 All OARs werelocked directionally for tomotherapy planning. On tomotherapy planning station,plans (with and without the strip bolus) were generated for each patient. Ino-bolus plans, strip bolus was contoured and overrode to air density before plan-ing. All plans were normalized to 95% of the chest wall volume receiving 100% ofhe prescribed dose. Dose-volume histograms (DVHs) were used to determine theaximum, minimum, and mean dose of the PTVs and critical structures. Megavolt-ge CT (MVCT) images of patients were acquired daily on the tomotherapy unitefore each treatment using 3.5-MV beam energy and 4-mm (normal mode) slicehickness. These images were used primarily for patient alignment to reduce setuprrors and allow accurate dose targeting.

praclavicular PTV

all Scar PTVMammary NodesPTV

Axilla-supraclavicularPTV

P Gy V (mL) P Gy V (mL) P Gy V (mL) P Gy

50.4 47.4 59.4 30.3 47.6 217.4 49.050.4 42.3 60.0 — — 88.2 50.450.4 51.5 59.4 31.0 47.6 138.9 47.649.3 40.9 58.0 11.5 45.0 — —50.0 41.6 57.5 35.5 45.0 217.3 48.850.4 27.6 60.2 15.6 47.6 239.2 47.6

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(mL)

3.63.68.03.94.31.6

— 41.9 — 24.8 — 180.2 —

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Y. Rong et al. / Medical Dosimetry 37 (2012) 233-239 235

Results

Daily setup verification

Figure 3 shows the registration of MVCT images with planningT in all 3 views (axial, coronal, and sagittal). Air gaps were stillresent with strip bolus but were more reproducible on dailyetup. Dose verification was done on the first day of treatmentsing the Planned Adaptive program (TomoTherapy, Inc.). For doseerification, the MVCT images obtained on the first day were used.he MVCT scan was registered with the original kVCT scan on thelanned Adaptive programwith the same shifts as were applied forhe treatment setup. Then the dose was computed on the MVCTmages using the planned sinogram from the kVCT-based plan. Theim of performing dose verification was to verify differences be-ween the planned and delivered doses. The discrepancies betweenhe verification dose and the planned dose were �2% in the targetregions for all 6 patients. An example is shown in Fig. 4. During thedaily image guidance for online patient positioning, tomotherapyonly allows position corrections in 3 translational axes and onerotational axis (roll). Therefore, it is necessary to check the residualposition errors offline using all 6 axes after each fraction. Accuratepositional corrections, taking into account the pitch and yaw axes,were further estimated offline on the Planned Adaptive program,by retrospectively matching the daily MVCT to planned kVCT care-fully so the verification dose is comparable (�1%) with the planneddose. The residual setup errors were obtained by subtracting the

Fig. 2. (A) Axial and (B) sagittal views of targets and critical structures

Fig. 3. Image registration of planning CT (gray) and MVCT (blue) for a patient in (A) axiarotational (roll) shifts were allowed.

actual shifts from the accurate ones. The accurate shifts were thosethat resulted in precise dose delivery compared with the planningdose. The average values were 1.1 mm (X), 1.3 mm (Y), and 0.8 mm(Z) in translational axes and 0.5� (roll), 0.5� (pitch), and 0.8� (yaw) inrotational axes. Patient setup with strip bolus is reproduciblethroughout the treatment. Also, thermoluminescence dosimeter(TLD) chipswere used to verify skin dose on the superior chest wall,inferior chest wall, and scar region (beneath the bolus). As shown inTable 2, the TLD measurements verified that the scar PTV received100.7% of the prescription dose on average where the strip boluswas applied and 4�9% of underdosing on the chest wall regionwhere no bolus was applied.

Dosimetric comparison

We have compared the dosimetric characteristics of chest wallplans using 2 different setup techniques with (a) no bolus and (b)strip bolus. The most prominent advantage is the improved dosehomogeneity and less hotspot for the scar PTV and chest wall usingstrip bolus, as shown in Fig. 5. For the patient shown in Fig. 5, theprescription dose is 60.2 Gy to the scar PTV and 50.4 Gy to the chestwall. The hotspots are minimal (103%) and located near the scarPTV regions. Figures 6 and 7 show one right-sided and one left-sided chest wall patients, respectively. Both plans in each figurewere normalized to 95% of the chest wall volume receiving 100% of

ding the chest wall, spinal cord, heart, lungs, and contralateral breast.

l, (B) coronal, and (C) sagittal views. For patient positioning, only translational and

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Y. Rong et al. / Medical Dosimetry 37 (2012) 233-239236

the prescription dose. Figures show comparable DVHs of the lungs,cord, and contralateral breast between the 2 techniques. Table 3hows the ratios of Dmax, D98% (dose received by 98% of the targetolume), and Dmean to the prescribed dose for chest wall, scar PTV,ammary nodes, and axillary-supraclavicular nodes. As we can see

n Table 3, the D98% and Dmean are comparable in both plans,whereas the maximum dose to the scar PTV in the no-bolus plan is111.4% of the prescription dose average over 6 patients comparedwith 106.6% in the strip bolus plan. The maximum dose to the chestwall is 5% higher in no-bolus plans compared with strip bolusplans. The maximum doses received by the mammary and axillary-supraclavicular nodes are comparable for both plans. Table 4 showsetailed dose indexes of OARs, including heart, lungs, contralateralreast, and cord. The dose difference is minimal for all OARs, with3% of difference between the 2 plans in each case.

iscussion

Widely adopted techniques for postmastectomy chest wall ir-adiation include “standard tangents,” electron fields, “reverseockey stick” fields, 30%/70% or 20%/80% mixes of photon/electronelds, and partially wide tangent fields. Most of these emphasizen improved dose to the PTV and minimal dose to the sensitivergans, i.e., heart and lungs, in an effort to avoid late toxicity. It isvident from the studies that the ipsilateral lung normally receivesmaximum of 105% of the prescribed dose with these conventionalrradiation techniques.25,26 With the helical tomotherapy system,

Table 2TLD measurements on the superior chest wall, inferior chest wall, and scar

Chest WallSuperior (cGy)

Chest WallInferior (cGy)

Scar PTV(cGy)

DP 180.0 180.0 215.01st measurement 156.4 178.8 215.52nd measurement 171.0 167.9 213.53rd measurement 165.7 169.3 219.04th measurement 162.9 174.5 218.3Average/DP 91.1 � 3.3 96.0 � 2.8 100.7 � 1.1

Fig. 4. DVH comparison between the verification (dashed lines) and planned doses (soand axilla-supraclavicular nodes PTV (dark red). The discrepancies between the verific

Measurement uncertainty is 3.6%.

the intensity of the 6-MV fan beam can bemodulated by a row of 64binary leaves projected to the isocenter. Also, 51 projections pergantry rotation assist the individual modulation patterns, whichare further optimized by the tomotherapy planning process. There-fore, tomotherapy can provide more uniform PTV coverage andreduces the acute toxicities by reducing the volume of OARs receiv-ing high-dose compared with conventional 3D conformalplans.28,32 A theoretic limitation of tomotherapy is the increasedecondary cancer complication probability (SCCP). The SCCP isigher with tomotherapy compared with the mixed-beam tech-ique for lungs (5.0% vs. 2.5%) and contralateral breast (1.6% vs..2%), which increases the risk of secondary cancer in young pa-ients (aged �30 years).27

Dose coverage near the skin is another factor to consider forpostlumpectomy and postmastectomy patients.With conventionalphoton beam irradiation, skin-sparing effect results in underdos-ing inside the tumor volume along the scar, which can be compen-sated by bolus materials.9,10 Plan comparison study shows thattomotherapy delivers higher superficial dose compared with otherconventional modalities.27 Therefore, skin-sparing techniquesave been suggested to reduce skin dose without compromisingoses to the breast target.35 Nevertheless, experimental studieshow that tomotherapy planning may overestimate the superficialose by 3–13% for postmastectomy chest wall plans.35,36 Possible

causes for these differences in the surface region may be heavilyweighted pencil beams to achieve sufficient surface dose coverageand failure of the convolution/superposition algorithm to accountfor reduced backscatter dose for highly oblique beams near thesurface.35,36 One cm of bolusmaterial covering the entire chest wallis recommended to ensure a greater accuracy in the calculated dosein the superficial target region. An ideal bolus material should beequivalent to tissue in both stopping power and scatteringpower.37,38 It should be placed on the patient such that there areinimal air cavities. Significant density heterogeneity caused by

he air cavities results in electronic disequilibrium and conse-uently affects dose to the chest wall by up to 10%,14,39 which

consequently counteracts the benefits of using bolus.Tomotherapy users have studied PMRT to a maximum dose of

s) for targets, including scar PTV (yellow), chest wall (orange), mammary nodes (red),ose and the planned dose were �2% in target regions for all 6 patients.

50 Gy (no integrated boost) without using bolus materials and ob-

(A) ax

Y. Rong et al. / Medical Dosimetry 37 (2012) 233-239 237

tained acceptable target dose conformity and homogeneity.27,30

However, significant hotspots were observed along the chest wallskin during our practice if SIB dose regimen was prescribed in to-motherapy planning, as demonstrated in the no-bolus plans in thepresent study. With all factors considered, we tested the use ofstrip bolus on 6 chest wall patients. The use of strip bolus providesimproved consistency in daily patient setup and surface dose accu-racy on the scar PTV by reducing air gaps between the bolus and

Fig. 6. DVH comparison for a right-sided chest wall patient using setup of (A) no-

Fig. 5. Final dose distributions on the planning CT for the patient shown in Fig. 3 inmastectomy scar regions.

bolus and (B) strip bolus. Targets and normal tissues, including lungs, left breast, andcords were compared.

skin surface. Doses delivered on the superior and inferior chestwall were shown to be 91�96% on average of the prescriptionwhen no bolus was applied, which is consistent with previous pub-lications.35,36 Results in Tables 3 and 4 demonstrated that with thestrip bolus setup, target dose uniformity can be greatly improved,especially for the scar PTV and chest wall targets, whereas no sig-nificant dose differences were observed for normal tissue doses

Fig. 7. DVH comparison for a left-sided chest wall patient using setup of (A) no-bolus

ial, (B) coronal, and (C) sagittal views; 62-Gy (103%) dose hotspots are located in the

and (B) strip bolus. Targets and normal tissues, including lungs, right breast, andcords were compared.

thapew

n

0.96

Y. Rong et al. / Medical Dosimetry 37 (2012) 233-239238

with or without the strip bolus. The in vivo TLD measurementsconfirmed sufficient doses to the scar PTV and are �90% of theprescription dose to the chest wall, whichwas considered clinicallyacceptable by the attending physician.

It poses a great difficulty when comparing the present study tothe existing literature,27-32 as this study is the first to report thepostmastectomy irradiation with integrated scar boost using to-motherapy. We have demonstrated the feasibility of tomotherapyfor delivering SIB to breast patients,18 followed by a recent studyproving that tomotherapy provides superior SIB dose coveragecompared with 3D conformal radiotherapy for breast patients.32

Significantly improved normal tissue dose sparing was reportedcompared with the present study, with a sacrifice in treatmenttime (22 minutes vs. 9minutes) resulting from the complete blockshat were applied for planning. Similarly, better dose sparing in theeart was achieved in Ashenafi et al.24 for 5 chest wall patients withprescription dose of 50 Gy to chest wall and nodal regions com-ared with the present study (heart Dmax: 23 Gy vs. 42 Gy). How-ver, dose to lungs and contralateral breasts are comparable, evenith a SIB up to 60.2 Gy in the present study. More studies28-31

compared tomotherapy with 3D conformal radiotherapy or elec-tron/photon IMRT for the whole-breast treatment or acceleratedpartial-breast irradiation with a prescription of 50.4 Gy to the tar-get. A similar conclusion has been reached that the helical tomo-therapy provides better dose conformity and homogeneity withhigh dosage sparing of heart and lung, but it can potentially pose ahigher risk of radiation-induced malignances caused by the in-creased volume of tissues receiving low doses. The present studyshows comparable dose sparing for heart, spinal cord, contralateral

Table 3Comparison of no-bolus and strip bolus plans for ratio of Dmax., D98% and Dmean to the podes

Dmax/Dp

No Bolus Strip Bolus

Chest wall 1.28 � 0.03 1.24 � 0.02Scar PTV 1.11 � 0.02 1.07 � 0.01Mammary nodes 1.10 � 0.03 1.12 � 0.06Axilla-supraclavicular 1.09 � 0.01 1.09 � 0.01

Table 4Normal tissue sparing in chest wall irradiation with different setup comparison

Variable

No-bolus Plan

Range

Deliver time (min) 7.7–11.5HeartDmean (Gy) 9.0–14.9Dmax (Gy) 33.8–48.7*V40Gy (%) 0.0–1.9*V30Gy (%) 0.2–8.2*V5Gy (%) 73.7–100.0

Total lungsDmean (Gy) 9.9–10.5Dmax (Gy) 51.8–59.8*V45Gy (%) 0.3–1.2*V20Gy (%) 7.3–11.1*V5Gy (%) 77.5–87.0

Contra-lateral breastDmean (Gy) 3.9–6.8Dmax (Gy) 14.8–31.2*V5Gy (%) 16.0–66.0

CordDmax (Gy) 7.7–27.1

* VxGy (%) is percentage volume receiving xGy or less.

breast, and lungs without significant increase in treatment time orsacrifice in target coverage, even with longer treatment lengthcaused by the positive nodal involvement and dose escalation inthe mastectomy scar region resulting from the SIB treatment regi-men. The literature comparison is listed in detail in Table 5. Usingthe strip bolus for these treatment sites further improves the qual-ity of tomotherapy plans in terms of setup reproducibility.

Conclusion

This is the first study to evaluate the feasibility of tomotherapy fordelivering postmastectomy radiotherapy with simultaneous inte-grated boost to themastectomy scar. Six patientswere studied for thesetup and dose calculation with and without the strip bolus. Usingbolus for chest wall patients has been a routine practice for years toensure sufficient dose calculated and delivered to the patient surface.However, using bolus on the entire chest wall would produce un-acceptable air gaps and variations in daily patient setup, whichposes a significant dose deficit to IMRT planning, especially fortomotherapy users. Therefore, using a trip bolus on the scar regiononly is a possible solution to ensure accurate dose calculation anddelivery to the mastectomy incision area that has the highest tu-mor recurrence rates.

The authorswould like to thankBeckyAdkins andVickiMullins fortheir assistance in the treatment process at our facility.

bed dose (Dp) for the chest wall, scar PTV, mammary nodes and axilla-supraclavicular

/Dp Dmean/Dp

olus Strip Bolus No Bolus Strip Bolus

� 0.01 0.97 � 0.02 1.08 � 0.02 1.08 � 0.02� 0.01 0.99 � 0.01 1.04 � 0.01 1.03 � 0.01� 0.01 0.97 � 0.01 1.04 � 0.01 1.04 � 0.02� 0.01 0.96 � 0.01 1.04 � 0.01 1.03 � 0.01

Strip Bolus Plan

� SD Range Mean � SD

1.4 7.6–11.5 8.9 �1.4

2.2 9.6–15.0 11.0 � 2.05.6 34.1–48.8 42.0 � 5.30.8 0.0–1.5 0.3 � 0.63.0 0.4–8.0 2.5 � 2.89.8 75.0–98.0 85.8 � 9.6

0.3 9.6–10.6 10.2 � 0.43.0 53.2–58.0 55.6 � 2.00.3 0.2–1.0 0.7 � 0.31.3 6.5–11.0 8.9 � 1.63.6 77.2–86.0 80.5 � 3.0

1.1 3.7–6.8 4.9 � 1.16.7 14.4–34.0 21.3 � 7.318.6 19.5–65.0 35.6 � 18.4

7.9 7.0–27.2 16.5 � 8.2

rescri

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No B

0.970.990.97

Mean

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11.1 �40.9 �0.3 �2.1 �

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10.2 �55.5 �0.7 �9.1 �

80.2 �

5.0 �22.2 �37.4 �

17.0 �

Y. Rong et al. / Medical Dosimetry 37 (2012) 233-239 239

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19. Rong, Y.; Paliwal, B.R.; Howard, S.P.; et al. Treatment planning for pulsed reduced

Table 5Studies comparison on tomotherapy dosimetry for chest wall or whole-breast irradiat

Studies# ofCases

Breast/CWDp (Gy)

Breast/CWPTV (cm3)

Integrated Boost(Y/N)/Dp (Gy)

Nodes Involvement(Y/N)/Dp (Gy)

Rong, et al. 6 49.3–50.4 374 Y/57.5–60.2 Y/45.0–50.4Ashenafi, et al.24 5 50.0 — N Y/45.0–50.0Gauer, et al.25 3 50.4 — N No (n � 2)

Yes (n � 1)/50.0Goddu, et al.27 10 50.4 1189 N Y/50.4Gonzalez, et al.28 5 50.4 691 N NHijal, et al.29 13 50.68 483 Y/64.4 N

Dp, prescription dose.* Estimated from the data provided in the paper.

dose-rate radiotherapy in helical tomotherapy. Int. J. Radiat. Oncol. Biol. Phys. 79:934–42; 2011.

20. Yadav, P.; Tolakanahalli, R.; Rong, Y.; et al. The effect and stability of MVCT imageson tomotherapy adaptive planning. J. Appl. Clin. Med. Phys. 11:4–14; 2010.

21. Welsh, J.S. Helical tomotherapy in the community setting: A personal account.Community Oncol. 6:463–7; 2009.

22. Hui, K.S.; Kapatoes, J.; Fowler, J.; et al. Feasibility study of helical tomotherapy fortotal body or total marrow irradiation.Med. Phys. 10:3214–24; 2005.

23. Hsieh, C.H.; Wei, M.C.; Hsu, Y.P.; et al. Should helical tomotherapy replace brachy-therapy for cervical cancer? Case report. BMC Cancer 10:637; 2010.

24. Lee, T.F.; Fang, F.M.; Chao, P.J.; et al. Dosimetric comparisons of helical tomotherapyand step-and-shoot intensity-modulated radiotherapy in nasopharyngeal carci-noma. Radiother. Oncol. 89:89–96; 2008.

25. Sonnik, D.; Selvaraj, R.N.; Faul, C.; et al. Treatment techniques for 3D conformalradiation to breast and chest wall including the internal mammary chain. Med.Dosim. 32:7–12; 2007.

26. Thomsen, M.S.; Berg, M.; Nielsen, H.M.; et al. Post-mastectomy radiotherapy inDenmark: From 2D to 3D treatment planning guidelines of the Danish Breast Can-cer Cooperative Group. Acta Oncol. 47:654–61; 2008.

27. Ashenafi, M.; Boyd, R.A.; Lee, T.K.; et al. Feasibility of postmastectomy treatmentwith helical TomoTherapy. Int. J. Radiat. Oncol. Biol. Phys. 77:836–42; 2010.

28. Gauer, T.; Engel, K.; Kiesel, A.; et al. Comparison of electron IMRT to helical photonIMRT and conventional photon irradiation for treatment of breast and chest walltumours. Radiother. Oncol. 94:313–8; 2009.

29. Oliver, M.; Chen, J.; Wong, E.; et al. A treatment planning study comparing wholebreast radiation therapy against conformal, IMRT and tomotherapy for acceleratedpartial breast irradiation. Radiother. Oncol. 82:317–23; 2007.

30. Goddu, S.M.; Chaudhari, S.; Mamalui-Hunter, M.; et al. Helical tomotherapy plan-ning for left-sided breast cancer patients with positive lymph nodes: Comparisonto conventionalmultiport breast technique. Int. J. Radiat. Oncol. Biol. Phys. 73:1243–51; 2009.

31. Gonzalez, V.J.; Buchholz, D.J.; Langen, K.M.; et al. Evaluation of two tomotherapy-based techniques for the delivery of whole-breast intensity-modulated radiationtherapy. Int. J. Radiat. Oncol. Biol. Phys. 65:284–90; 2006.

32. Hijal, T.; Fournier-Bidoz, N.; Castro-Pena, P.; et al. Simultaneous integrated boost inbreast conserving treatment of breast cancer: A dosimetric comparison of helicaltomotherapy and three-dimensional conformal radiotherapy. Radiother. Oncol. 94:300–6; 2010.

33. Javedan, K.; Zhang, G.; Mueller, R.; et al. Skin dose study of chest wall treatmentwith tomotherapy. Jpn. J. Radiol. 27:355–62; 2009.

34. Recht, A.; Hayes, D.F.; Eberlein, T.J.; et al. Local-regional recurrence after mastec-tomy or breast-conserving therapy, In: Harris, J.R.; Lippman, M.E.; Morrow, M.; etal., editors. Diseases of the breast. Philadelphia: Lippincott; 1996: 649–67.

35. Ramsey, C.R.; Seibert, R.M.; Robison, B.; et al. Helical tomotherapy superficial dosemeasurements.Med. Phys. 34:3286–93; 2007.

36. Cheek, D.; Gibbons, J.P., Rosen, I.I.; Hogstrom, K.R. Accuracy of TomoTherapy treat-ments for superficial target volumes.Med. Phys. 35:3565–73; 2008.

37. Saibishkumar, E.P.;MacKenzie,M.A.; Severin, D.; et al. Skin-sparing radiation usingintensity-modulated radiotherapy after conservative surgery in early-stage breastcancer: A planning study. Int. J. Radiat. Oncol. Biol. Phys. 70:485–91; 2008.

38. Lambert, G.D.; Richmond, N.D.; Kermode, R.H.; et al. The use of high density metalfoils to increase surface dose in low-energy clinical electron beams. Radiother. On-col. 53:161–6; 1999.

39. Ito, S.; Parker, B.; Gibbons, J.; et al. Analysis of chest wall in-vivo dosimetry for

tmente (min) Heart Dmean (Gy) Heart Dmax (Gy)

LungsDmean(Gy)

LungsV20Gy(%)

ContralateralBreast Dmean(Gy)

Cord Dmax(Gy)

11.0 42.0 10.2 8.9 4.9 16.5— 23.0* — 8.8* 2.9 —13.5 33.8 35.5* 11.1* 7.3 —

12.2 45.0* 7.6 7.9 4.3 —— — — 11.0* — 12.0*1.4 (left-sided,

n � 8)26.5 (left-sided,

n � 8)2.2* 3.2* 0.5 —

ion

TreaTim

8.921—

—6–922.3

post mastectomy radiotherapy using helical tomotherapy. Med. Phys. 36:2600;2009.